Greetings community. I am working on a computer that has a motherboard and some expansion slots for expansion cards. I currently build the expansion boards with this type of male connector which goes into the motherboard with the associated female.
What are folks thoughts? I know, for one, my approach is not keyed and the board can be put in backwards.
If the later approach is generally preferable, what type of connector system is this called?
What do I search for for the female that goes on the motherboard.
Are there any tutorials on line that show how to layout the PCB to make the male version of this like in the 2nd photo.
But notice that you should know what are the requirements for aging, reliability etc. If you want a “real” connector, the edge should be chamfered and the pads gold plated. That probably costs you extra. See for example Edge Connectors - Eurocircuits.
Female connector parts can be found by searching for “edge connector” or something like that. Prices may vary wildly.
The pin header is probably the cheapest and easiest option, especially for prototypes and hobby use. On the other hand, for cheap prototyping you could do without beveling and gold plating.
Good to know. My only reason for investigating this was that I was having issues with good connections on all pins in my current approach. After much investigation it appeared that after production there was some type of residue, maybe solder flux, on some of the pins. Consequently, when I get my boards I need to take a toothbrush and isopropyl alcohol to clean them. When I put these connectors on my self I never have seen this issue but for my classes where we use these boards I just dont have the time to do all that soldering on some 20+ boards :-). I was thinking the tighter fit of the PCI connector might strip away any residue as part of the insertion process. But wasn’t sure.
I tend to agree with the conclusions here. Card edge connectors with gold plating and chamfering are easy for mass production, but a nuisance for small production runs.
Using double row headers is a logical connector for DIY and low volume, but there are significant differences in quality between brands. Both in plating of the male pins, and in the internal construction of the female contacts, and this very likely has a significant effect on the mating cycles these can handle.
In my own design I used 40 pin male boxed headers on the extension cards, and a 44 pin dual row female header on the backplane. The extra 4 pins have no electrical connection, but they fill up the “extra space” in the box header and this makes it impossible to insert them 1 pin “off”. (Only 180 degrees rotated is still possible).
Also, with standard square pins and 2.54mm pitch you can stay compatible with standard flatcables. This can be handy as a “riser card” for when you need to troubleshoot or repair a card on the bus.
I don’t really understand why there would be flux on the connecting part of the connector. Flux is normally applied to the solder location, and that is on the other side from the big plastic part of the connector. Maybe it was just a bad batch, too cheaply sourced connectors or a sloppy manufacturer.
If I was outsourcing manufacturing, I would expect connectors to be clean and working when I receive the product. Flux does splatter a bit sometimes, especially when the PCB is out gassing during soldering and that could be the cause. If you do this more often, the best way is probably to make a few photographs of the issue, contact your manufacturer, and ask them what they can do to prevent this from happening the next time. Personally I prefer to mate connectors before soldering (you can use a few spare connectors for this purpose) This does two things. First it cools the mating part of the connector because of the higher thermal mass, and this reduces melting of the plastic parts, and even if the plastic parts get hot enough to become soft, it holds the pins in place and reduces distortions.
